Analysis - The Institute for Southern Studies

Exhibit 5A-10
Present Value of Avoided Human Cancer Risks Associated with CCR Disposal
($millions present value over 50-years)
Discount rate Subtitle C Subtitle D Subtitle D’
@ 3% $1,825 $750 $375
@ 7% $504 $207 $104
The other major cost associated with groundwater contamination is that of remediation or other response. To estimate that cost, EPA began by
estimating the number of coal-fired electric utility plants that would require responses under various state environmental programs, based on
the 2009 risk assessment. In any particular situation, a state could require remediation of a site involving potential drinking water to 10 -4 , 10 -5 ,
or 10 -6 levels. In addition, states may choose to require groundwater remediation for groundwater that is not a likely drinking water source,
because of ecological concerns. Exhibit 5A-11 below shows the number of facilities potentially requiring cleanup. Since each estimate is
equally acceptable under current state programs, the average is believed to be a best estimate for how many electric utility plants will ultimately
need groundwater remediation so as not to overestimate the number of remediation events.
State
Cleanup
Levels
Exhibit 5A-11
Proportion of CCR Sites Requiring Remediation Based on State Cleanup Levels
Clean All Groundwater
Clean Only Drinkable Groundwater
10 -4 10 -5 10 -6 10 -4 10 -5 10 -6 Average
Total LF 22 50 72 7 16 24 32
Total SI 93 132 150 31 44 50 83
These plant counts are based on the probabilistic model iterations from the 2009 risk assessment which were used to estimate what fraction of
sites would leach at above various clean up levels. Typically, solid waste cleanups can be conducted at either 10 -4 , 10 -5 , or 10 -6 individual
cancer risk levels. Exhibit 5A-12 uses the PERCENTRANK function in Excel to estimate what percent of risk results fall at or below each
clean up level. For example, in the first cell of Exhibit 5A-12, the 78% means that 10 -4 is higher than 78% of the probabilistic results for
unlined landfills with conventional ash.
UL = Unlined
CL = Clay-Lined
A = Conventionally Managed Ash
C = Co-managed Ash
LF = Landfill
SI = Surface Impoundment
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